Late last year, I blogged about a popular Joomla component that contained hidden advertising links. 

Since then more people have contacted us about other extensions that employ the same dirty trick. 

Which Extensions Have Been Found With Hidden Links?

• Joomap and XMap: see our previous post.
• Joomlart's Transmenu: click to see how many sites are hiding links they don't know about.
• Smoothgallery: contains three hidden links, only one to the developer.
• Artio SEF: contained hidden links to European hotels and other unrelated sites.
  
• AddThis Social Bookmarking: hidden link recently removed after complaints.
  
• Fireboard searchbot: it places an ad for the developer as the first result in all searches made on your site. There is no disclosure but there a small option inside the mambot to turn if off.

Why Is Hidden Advertising a Problem?

1. From a moral perspective, you have the right to know who or what is linking from your site.
2. Technically you'll be in violation of Google's guidelines.
   
   Whether or not sites will be penalized is a question thats difficult to determine, but the violation is clear:
   
   "If your site is perceived to contain hidden text and links that are deceptive in intent, your site may be removed from the Google index, and will not appear in search results pages. When evaluating your site to see if it includes hidden text or links, look for anything that's not easily viewable by visitors of your site. Are any text or links there solely for search engines rather than visitors?"
   http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=66353
   

Why Do Developers Do It?

Why do they create the links? Some extensions such as Joomlart's TransMenu have produced over 1.6 million links back to the developer. I doubt if 1% of those site owners realize they are providing those links.

Why do they hide it? Developers feel that if they put the link in a visible place, people would edit it out of the code and they wouldn't get their "reward". One developer actually spells this out in his code:

"Visitors don't see it, but search engines do. We appreciate backlinks, please consider this your thank you."

What is the Solution?

I'd like to propose a couple of possible answers:

1. Hidden advertising be added to the list of Extension Directory rules. Components with hidden links would be subject to the same three step penalty process as others who break those rules. Rather than immediately penalizing any of the extensions above, the developers could be given a month to come into compliance.




2. Longer term, perhaps we could include Joomla Credits in the Joomla core with a link to it from the Main Menu. People who don't want it displayed can simply unpublish the menu link. This would make it easy for everyone to understand who they are linking to. It would also mean that Joomla developers could give away their products and perhaps get even more links than they do now, without needing to be deceptive.